This invention relates to agricultural ground treating devices, and while it is particularly described in this specification in its application to seed drills for the direct drilling of seeds into the ground, the invention finds application in other similar ground treating devices which are arranged to be towed over the ground and have a plurality of ground engaging implements.
In agricultural devices having a number of ground engaging implements, when the device is towed over uneven ground problems arise from a lack of uniformity in the engagement of the implement on the ground. In the particular example of a seed drill, the device typically comprises a chassis arranged with wheels so that it can be towed over the ground and a number of ground engaging implements in the form of individual seed drilling units carried on the chassis to engage the ground. These units include means for cutting a slot or furrow in the ground and implanting seeds at spaced intervals along the furrow. The means for cutting the furrows are forced into the ground with a force dependent upon the depth to which the particular furrow is required and are often provided with surface engaging skids to assist in the control of the depth of cut. In existing machines all the cutting devices are loaded by a common mechanism to be forced into the ground, and thus where the device is towed across uneven ground difficulties arise in some of the cutting devices tending to cut deeper than others resulting in a lack of uniformity in the sowing of the seeds in the ground.
Accordingly the present invention seeks to provide improved means for raising and lowering the ground engaging implements on such an agricultural device and to control the force with which the implements engage the ground.